The diagnosis of a right lung biphasic pulmonary blastoma with large right lung mass and hilar/mediastinal lymphadenopathy was made on the basis of imaging and bronchoscopy guided biopsy. The patient received neoadjuvant chemo/radiotherapy with 4 cycles of carboplatin and etoposide before proceeding to have a right middle and lower lobe lobectomy (histology below). Following surgery they then received adjuvant chemotherapy with 4 cycles of carboplatin and etoposide.

Histology Report:

Histological tumor type: Pulmonary blastoma.

Tumor size:
- Tumor bed: 105mm (macroscopic measurement).
- Residual viable tumor: Scattered microscopic foci identified over an area measuring approximately 60mm (reconstructed measurement); largest microscopic focus in a single section measures 12mm. Treatment effect: 5% residual viable tumor; 10% fibroinflammatory stromal tissue; and 85% necrosis.
Visceral pleural invasion: Absent.
Lymphatic invasion: Not identified.
Vascular invasion: Not identified.
Perineural invasion: Not identified.
Spread through airspaces (STAS): Not identified.

Peribronchial/Hilar lymph nodes:
- Specimen 1. Right middle and lower lobe: Involved. Residual viable tumor is present with treatment retreatment related changes present (see microscopic comments above).
- Specimen 4. Right no. 11 lymph node: No evidence of malignancy. No evidence of treatment related changes.

Mediastinal nodes:
- Specimen 2. Right no. 4 lymph node: No evidence of malignancy. No evidence of treatment related changes.
- Specimen 3. Right no. 7 lymph node: Involved. Residual viable tumor is present with treatment retreatment related changes present (see microscopic comments above). The lymph nodes otherwise show reactive changes, with sinus histiocytosis and carbon pigment deposition.

PATHOLOGICAL STAGE (AJCC 8th ed):
ypT3: Tumor greater than 5cm but less than 7cm.
ypN2: Metastasis in ipsilateral mediastinal lymph node.
pR0: Complete resection, margins histologically negative, no residual tumor.

Immunohistochemistry:
- ALK: Negative
- ROS1: Negative.
- EGFR: No variant detected. No variant detected in BRAF or KRAS.
- PD-L1 TPS: 0%.
The tumor block contains ~60% viable tumor cell nuclei with dissection.

SUMMARY
1-4. Right middle and lower lobe; No. 4, No. 7 & No. 11 lymph node right lung:
- Scattered microscopic foci of residual viable pulmonary blastoma, present over an area measuring 60mm size (tumor bed 105mm).
- Neoadjuvant treatment effect: 5% residual viable tumor; 10% fibroinflammatory stromal tissue; and 85% necrosis.
- Viable metastatic tumor within peribronchial and separately submitted No. 7 lymph nodes.
- No evidence of malignancy in separately submitted No. 4 & No. 11 lymph nodes.
- Stage (AJCC 8th ed.): ypT3 N2
- Residual tumor status: pR0 (margins clear).